How radar works in aircraft

Radar basics and the doppler shift

NEXRAD (Next Generation Radar) obtains weather information (precipitation and wind) based upon returned energy. The radar emits a burst of energy (green in the animated image).

If the energy strikes an object (rain drop, snowflake, hail, bug, bird, etc), the energy is scattered in all directions (blue). Note: it's a small fraction of the emitted energy that is scattered directly back toward the radar.

Learn about the Radar Beam here

This reflected signal is then received by the radar during its listening period.

Computers analyze the strength of the returned pulse, time it took to travel to the object and back, and phase, or doppler shift of the pulse. This process of emitting a signal, listening for any returned signal, then emitting the next signal, takes place very fast, up to around 1300 times each second!

NEXRAD spends the vast amount of time "listening" for returning signals it sent.